Loud-speaker



Aug. 19, 1930. W, SEFTON 5T Al. 1,773,605

LOUD SPEAKER 'Filed May 18y 1927 f 1 Wm Patented Aug. 19, 1930 UNITEDSTATES PATENT OFFICE LOUD-SPEAKER Application filed Hay 18, 1927. SerialNo. 192,256.

This invention relates to certain new and useful improvements in loudspeakers.

T he main object of the invention is the pro-- duction'oi:` a loudspeaker of improved characteristics in the production and amplifica--tion of sounds, especially in that the reproduction is clearer, moredistinct and accurate, particularly as to sounds of comparatively lowpitch, and sounds of comparatively high pitch.

A further advantage resides in the provision of two diaphragms ofdifferent sizes and formed of dierent materials and each adapted formore eective reproduction of sounds of articular pitches.

ther objects and advantages relate to the details of the structure andthe arts thereof, all as will more fully appear trom the followingdescription, taken in connection with the accompanying drawings, inwhich:

Fi ure l is a front elevation of an apparatus o this invention.

Figure 2 is a sectional view on line 2 2, Figure 1.

Figure 3 is a. sectional View similar to Figure 2, but of a somewhatmodified form of apparatus Loud speaking devices, including'a conediaphragm and a motor for actuating the same, are well-known, and in thea paratus here shown the motor is generally illustrated at -A-. The formand structure of the motor forms no portion of this invention, and anyof the commonly used motors may be provided.

The apparatus as illustrated in Figures l and 2 comprises a hollowcircular frame 1 mounted on a base -Q-. One of the diaphragrns, as -3-,has its outer `edge clamped to the frame --1-- and the diaphragm itselfis of frusto-conical form, and is preferably made from some suitablepaper, such as stencil aper.

he diaphragm -3- as illustrated, 1s of annular form,'andrlp\rovided withan opening at its center. is opening is closed by a second or innerdiaphragm -4- as shown of conical shape and preferably formed of amaterial such as sheet-metal suiiiciently thin to constitute a vibratorybody for accurately reproducing tones or sounds of comparatively highpitch.

The outer edge of the metallic diaphragm --4- may be secured to theinner ed e of the paper diaphragm -3- in an suita le manner, as byover-lapping the e ges of the dia-- phragms and securing them togetherin overapped position by an adhesive or'other suitable means. Themetallic diaphragm J1- at its central portion may be formed with a hub 5mounted upon actuating rod -6- connected in the usual manner to themotor A and suitable connection may be made between the red (5- and thehub -5- as by means of a set screw --7.

This construction of apparatus is found highly eicient in the accuratereproduction of sounds of varying pitch as the outer paper diaphragm -3acts eectively to repro-- duce the tones of lower pitch, While-theiniier diaphragm --4- acts to effectively re-l proflluce the tones ofcomparatively high pito f In Figure 3 modified form of apparatus isshown in that the two diaphragms, altho actuated simultaneously from thesame motor A, are arranged separately.

The apparatus of Figure 3 comprises the same frame -1-, base --2 andmotor A, but the diaphragm t3- is in this structure a substantiallycomplete cone, and is mounted at its central portion in any suitablemanner upon the rod -9- connected to motor A. The diaphragm 8 ispreferably formed of suitable paper, such as stencil paper, Iandconstitutes in itself a complete operable apparatus, but in additionthereto a second ,diaphragm -10 is provided which may be flat, as shown,or of other forms, secured at its central portionto the rod -11- in anysuitable manner, so as to be actuated by the latter from the motor Asimultaneously with the actuation of the rod -9-.

The edge of diaphragm l0- may be clamped between the rings 12- and -l3-,the latter of which may be carried from the frame -1-- in any suitablemanner, as by brackets 14-. In this structure both diaphragm arranements are operable struc- Vtures in themse ves, but are simultaneouslyactuated to produce unitary sound, the diaphragm -8- acting to moreeectively reproduce the lower tones, while the diaphragm -lO- which ispreferably formed of thin sheet metal, and is of lesser diameter, actsmore effectively to reproduce the higher tones.

Altho we have shown and described specific structures as constitutingperhaps preferred embodiments of our invention, it will be apparent thatvarious and other modifications may be made in the details of thestructure,and the forni and arrangement thereof, all within `the scopeof the appended claims.

W'e claim:

l. A loud speaker including a diaphragm comprising two concentricconnected vibratory members formed of different material and havingportions which do not overlap.

E2. A loud speaker including a diaphragm comprising two concentricconnected vibratory members formed of different material and eachhavingt a portion free to vibrate without contact with the other, andmeans for simultaneously actuating the vibratory members.

3. A loud speaker comprising a cone diaphragm consisting of twoconcentric vibratory sections formed of different materials, one 01'said sections being of irusto-conicai form and the other being in theshape of a cone closing the central smaller opening of the othersection.

i. A loud speaker comprising a cone diaphragm consisting of twoconcentric vibra- 'tory sections of different sound reproducingcharacteristics, one of said sections being or' :truste-conical form,and the other being formed of thin metal in the shape of a cone closingthe central smaller opening; of the other section and secured to theadjacent edge thereof.

A loud speaker including a cone dia phragm comprising two sections, theouter one ot' which is i'rusto-conical and the inner one of which isconical, and closes the smaller open end or" the other section.

5. i loud speaker including a cone diaphragm comprising two sections,the outer one of which is 'frusto-conical and the inner one ot which isconical and closes the smaller open end of the other section, and isformed or thin sheet metal.

in witness whereof we have hereunto set our hands this 12th da;v of May,1927.

PENNNGTN SEFTN. TVVELFRED SEFTUN.

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